Edwaed murphy



('No Model.)

' -E. MURPHY.

AUTOMATIC TENSION DEVICE FOR SEWING MACHINES.

lPatented Dec. 18, 1883 N. PETERS. PhoM-Lflhogmphu. washin gen. 0 Q

' UNRTED STATES PATENT, @rrrcn.

EDWARD MURPHY, OF NEW YORK, N. Y., ASSIGNOR TO THE KRU S E 8t MURPHYMANUFACTURING COMPANY, OF SAME PLACE.

AUTOMATIC TENSION DEVICE FOR SEWING-MACHINES.

SPECIFICATION forming part of Letters Patent No. 290,345, dated December18, 1883.

v Application filed August 30, 1883. (N0 model.) I

To all whom it may concern..-

Be-it known that I, EDWARD MURPHY, of the city, county, and State of NewYork, have invented a new and useful Improvement in Automatic TensionDevices for Sewing-Machines; and I do hereby declare that the followingis a full and eXact description thereof, reference being had to theaccompanying drawings, and to the, letters of reference marked thereon,making a part of this specification.

My invention relates to that class of tension devices for sewingmachines in which the thread is firmly held until the loop or stitch isnearly or wholly drawn up tothe material, and is then wholly released orheld less firmly during the remaining movements of the needie, by meansof which a proper tension is obtained automatically, whatever may be thesize of thread, length of stitch, or thickness and nature of thematerial to be sewed, without requiring a separate adjustment for itsadaptation to the constantly varying requirements of the work. Ingeniousdevices adapted to effect this object have been heretofore employed; butwhere effective they have involved a multiplicity of parts, expensive inconstruction and more or less cumbersome.

The object of my invention is to provide a neat, sensitive, positive,and quickly operative device, including the fewest possible elements,and which may be compactly arranged and concealed upon the frame andoperated directly by the oscillations of the needle-arm.

It consists in employing a curved springplate firmly secured at one endto the under side of the arm of the frame, and which extends to and isoperated at its other end by a cam or shoulder oscillating with theneedle arm, for the purpose of actuating one of two bearing-disksplacedupon thetop of the frame, and betweenwhich the thread is passed,asmore particularly pointed out in the claims, whereby said disk ispressed closely upon the other by the tension of the spring when it isactuated by the cam on the needle-arm, but is otherwise left free topress loosely thereon and allow the thread to pass freely between thedisks, the cam being so arranged and adjusted relatively to theneedle-arm as that the spring plate and tension will not be influencedthereby, ex-

cept at the time when in the movements of the needle the loop is beingdrawn up to the cloth.

In the accompanying drawings, Figure 1 is a view in elevation of asewing-machine with my improvement attached, showing the needle in itsdescent and the tension-spring about to be acted uponto hold the thread,a portion of the needle-arm being broken away to show the cam whichoperates the tension-spring. Fig. 2 is a plan view of a part of theframe of the machine and needle-arm, the course of the thread from thespool around the tension device being illustrated in dotted lines; Fig.3, atransverse sectional View in the line 3 y of Fig. 1, showing thetensionspring and its connection with the needle -bar frame, needle arm,and tensiondisks; Fig. 4, a detached front elevation of the face-plate,needle-bar, and pressure-foot bar,

illustrating the form and location of the takeup device used incombination with my automatic tension.

Myinvcntion is applicable to all sewing-machines in which the needle isoperated by the action of an oscillating or vibrating arm.

A represents the needle-arm of a sewing-machine, C, a pivot secured toand projecting from the fixed arm B of the frame, and upon which theneedle-arm is made to oscillate by means of a link, D, connecting withan eccentrio on the main shaft E. R represents the spool support orcarrier projecting from the arm B at its rear end, T, Fig. 4, the springtake-up, by which the slack of thread is taken up as the needle rises.

The tension device consists simply of two separate superimposed rings orannular disks, F G, (see Fig. 3,) of which the lower one is fittedloosely in an encircling-recess formed in a boss, H, on the upper sideof the arm'B of the frame, preferably about midway its length. A rod, J,passes loosely through the central aperture in the two disks and throughan aperture pierced centrally through the boss and the arm. The upperend of'the arm is threaded to engage a cap-plate, L, which fits over theupper disk, F, and an outer lock-nut, M, which screws down upon saidcap-plate. lower end of the rod is secured to a curved spring-plate, N,made fast at one end by a screw or other device to the under side of theThe IOO

arm B of the frame, at a point preferably about midway between thetension-rod J and the needle-bar, and which is extended thence under thearm B to a point in line with the pivotal axis of the needle-arm A,where it is made to bear with its elastic tension against a cam-disk orring, I, secured by means of a set-screw firmly on theinner side of theneedlearm to its pivot-pin C, so as to oscillate therewith, or, if thepivot-pin be fixed, then to the needle-arm itself, to vibrate therewithupon said pin. The cam P is formed with two surfaces of different radii,each concentric with its axis, and which are connected by a suddenincline, and the end of the spring is made to bear against saidsurfaces, so as to be forced out by the one and allowed to drop inwardby the other. e

The adjustment of the tension-rod J to the disks F G and the spring N isso determined as that, when the spring is forced out by the largerportion of the cam, the rod will be drawn down thereby with sufficientpressure to draw down and bind the upper disk, F, firmlyupon the lowerdisk, G; but when by the oscillation of the cam the spring is left freethe tension upon the rod J is removed, and the rod is slightly lifted bythe elasticity of the spring, leaving the disks loose, and the upper onebearing upon the interposed thread with simply the pressure due to itsweight. The cam P is so adjusted with reference to the needle-arm asthat the oscillating movements of the arm shall operate to force andbear out the spring N while the needle is completing its downwardmovementand making its upward movement, and until the loop is almost orquite drawn up to the cloth, and then to suddenly release it so soon asduring the upward movement this is accomplished. The thread ispreferably passed, in the direction shown by dotted lines in Fig. 2,from the spool upon the spool-support R forward around the rod J,between the disks F G, thence back through the guide-wire S, secured tothe spool support R, and again forward through the eye S upon theneedle-arm, the guide-wires S upon the upper end of the face-plate, and8 upon the upper end of the needle-bar. through the take-up T, andfinally to and through the eye of the needle. The thread may beconducted from the spool through the tension device and to the needle inany other suitable manner without departing from my invention, and thetension spring and disks may obviously be secured to the oscillatingneedle-arm in a manner similar to that of its attachment to the arm B ofthe frame, as shown in the drawings; but such a modificationnecessitates the use of a fixed cam si'cured to the arm B at the pivotalpoint of the needle-arm, in stead of to the needle-arm itself, tovibrate therewith.

The operation of this simple automatic tension is as follows: Afterbeing led from the spool to the needle in manner as above described, andas shown by dotted lines in Fig. 2, the thread will, during theoperation of forming the stitch, be firmly held between the disks F G bythe tension of the rod J upon the disk l produced by the outward throwof the spring-plate N by the pressure thereon of the enlarged portion ofthe cam P. So soon, however, as the stitch is completed and the loopproperly drawn up, the oscillation of the needle-arm having the cam willcarry its reduced portion by the end of the spring, and thus release itsuddenly, and its resiliency will cause it not only to release the rod Jfrom the tension, but lift it slightly, so that the only friction nowexerted upon the thread in passing between the disks will be the weightof the upper disk, which is sufficiont to prevent an excess of threadbeing drawn off of the spool.

I do not claim, broadly, an automatic tension in a sewing-machinecomprising a springplate actuated by a cam moving in unison with thestitch-forming devices to produce an intermittent pressure upon thethread in the machine. My improvement relates especially to thecombination of devices herein described, by means whereof an automatictension is simply and effectively produced in machines constructed withan oscillating needle-bar.

I claim as my invention The combination, with annular tensiondisks F G,superimposed upon the fixed arm B of a sewing-machine frame, and with acentral rod, J, attached to a cap-plate resting upon said disks andpassing loosely through the disks and arm, of an elastic plate, N,fitted beneath said fixed arm, and which, being secured thereto at apoint between the rod J and the needle-bar, engages the rod, and extendsthence under the arm B to the pivot of the oscillating needle-arm A, tobear against and be actuated by a cam upon the inner side of said arm,substantially in the manner and for the purpose herein set forth.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

EDlVARD MURPHY. lVitnesses:

A. WV. STEIGER, J. F. ACKER, Jr.

